Understanding the causes of heart disease in DMD

Joining Jack has granted £86,460 to consultant cardiologist Dr John Bourke at Newcastle Hospital, to carry out a study of Arrhythmias to improve understanding of the causes of heart disease in DMD.

Joining Jack, Duchenne UK and Alex's Wish - Conquering Duchenne, are jointly funding this study.
Dr Bourke wants to understand the impact of arrhythmias (heart rhythm problems) in DMD patients, particularly adolescents and adults living with DMD who have previously shown no symptoms of arrhythmias.
Alex Johnson, our co-founder and Jack's mum, said: “We are very pleased to be funding Dr Bourke and this study. He is incredibly dedicated to working to help improve cardiac outcomes for patients with DMD. We hope this study will provide evidence of the potential benefit of using devices like pacemakers and can impact life expectancy if patients are monitored and have a device fitted earlier than they would usually do”.
Jon Hastie, CEO of DMD Pathfinders and adult living with DMD, said: “This project looks really interesting. I would say the project is needed as cardiac failure is such a significant cause of death and we definitely need to understand it more.”
This project aims to address the following:

Quantification of extent, distribution and architecture of cardiac scarring
Compare scar burden/characteristics between BDMD patients and patients with myocardial infarction with similar heart function.
Finally, to understand and define whether the prevalence of such minimally or non- symptomatic tachy/brady-arrhythmias is the same in BDMD patients with left ventricular systolic dysfunction.
Read Sejal, one of our advocacy Support Officer’s, advice on heart medication in her blog:

https://www.duchenneuk.org/heart-to-heart-blog

Arrhythmias Q&A:

Q: Why is this project so important?

A: Progressive muscle-weakness of the heart (cardiomyopathy), culminating in 'pumping-failure' with symptoms is a significant cause of death in people with Duchenne muscular dystrophy. However, sometimes death occurs unexpectedly - without any prior heart symptoms and when quality of life is good. There are a variety of possible heart and 'non-heart' reasons why death might happen suddenly in this way. This project is designed to study the most likely cause of sudden deaths by defining the prevalence of asymptomatic 'warning' disturbances of heart rhythm (arrhythmias) in patients with DMD. The findings will determine whether using implantable devices such as defibrillators or pacemakers to treat arrhythmias in DMD could prevent cardiac arrests due to cardiomyopathy. Treatment with these devices is known to prolong survival in non-DMD patients with similar degrees of heart pumping weakness. However, implantable-defibrillators are not usually considered for patients with DMD. By looking systematically for ‘background arrhythmias’ which are not yet apparent to the patient and not sought by routine clinical checks currently, the findings will determine for the first time the prevalence and likely contributors to sudden cardiac death from 'run-away' fast or slow heart rhythms in DMD. This information is key to designing strategies for prevention.

Q: Who will benefit from this study?

A: The adults who take part in the study will benefit directly from the comprehensive cardiac monitoring they will receive through the study design. The small 'chip' implanted under the skin for the research provides 24/7 heart-rhythm surveillance and communicates any abnormalities automatically to a central monitoring station. This degree of heart rhythm surveillance is way above and beyond what is done currently as part of routine DMD heart checking.

The wider Duchenne community will also benefit in the longer term through the improved understanding of the contribution of cardiac arrhythmias to deaths in patients with DMD. The results will determine, for example, whether adding device-therapy - such as pacemakers, to the medicines already used now could improve outcomes further by preventing sudden deaths from cardiomyopathy (progressive heart weakness and 'electrical instability') in patients with DMD.

Q: How could this project translate into finding a treatment for Duchenne muscular dystrophy?

A: Depending on the results we get from the study, it may show that DMD patients could benefit from either implantable defibrillator therapy or pacemaker therapy. If arrhythmias are not detected, the focus for further research would move to considering the role of pulmonary embolism (blood clots) as the cause of unexpected heart failure and the use of blood thinning therapies to prevent this.